To provide a data logger for inputting a command for display or the like by a manual operation, using an acceleration sensor for measuring an acceleration caused by disturbance.

This data logger comprises the acceleration sensor, a sensor for measuring a physical quantity such as a temperature sensor, a display body, a memory, a microprocessor, an electric power source and an external connection terminal. The measured physical quantity is stored in the memory, is transmitted to an external personal computer or the like via the external connection terminal, and is displayed on the display body. An acceleration model corresponding to the operation command of the data logger is stored in the memory. The propriety of correspondence, to the acceleration model, of an acceleration signal generated by the predetermined manual operation such as longitudinal, lateral or vertical movement, inclination or rotation is determined to execute the change of a display content on the display body and the change of an operation mode or the like, by the manual operation of the data logger.